Unary Adsorption Equilibria of Hydrogen, Nitrogen, and Carbon Dioxide on Y-Type Zeolites at Temperatures from 298 to 393 K and at Pressures up to 3 MPa

The equilibrium adsorption of CO2, N2, and H2 on commercially available Zeolite H–Y, Na–Y, and cation-exchanged NaTMA–Y was measured up to 3 MPa at 298.15, 313.15, 333.15, 353.15, and 393.15 K gravimetrically using a magnetic suspension balance. The chemical and textural characterization of the materials was carried out by thermogravimetric analysis, helium gravimetry, and N2 (77 K) physisorption. We report the excess and net isotherms as measured and estimates of the absolute adsorption isotherms. The latter are modeled using the simplified statistical isotherm (SSI) model to evaluate adsorbate–adsorbent interactions and parametrize the data for process modeling. When reported per unit volume of zeolite supercage, the SSI model indicates that the saturation capacity for a given gas takes the same value for the three adsorbents. The Henry’s constants predicted by the model show a strong effect of the cation on the affinity of each adsorbate.


S1 Bulk gas density measurements
C O 2 / Z S M -5 a t 2 9 3 K ( a ) A l i q u o t 1 r u n 1 A l i q u o t 1 r u n 2 A l i q u o t 2 r u n 1 A l i q u o t 2 r u n 2 P r e s s u r e , p [ M P a ] C H 4 / Z e o l i t e Y a t 2 9 8 K ( b )   We compare the SSI model with the commonly used dual-site Langmuir (DSL) model 4 .The model is given by:

S12 Virial isotherm model and fitted parameters
The virial equation is given by the following equation 5,6 for each component i: where a and b are the virial coefficients for a gas-solid system.In this study, we used M 1 = 3 and M 2 = 1 to provide a good fit.The Henry constant K can be approximated from a 0 and b 0 using the following equation: The equilibrium data were fitted to the virial equation and the uncertainty bounds were calculated using the same procedure described in Section 2.4.2 of the main text.The fitted parameters for the three materials are listed below in Table S2.
Table S2: Virial isotherm model parameters derived from fitting the low pressure volumetric CO 2 equilibrium data shown in Figure S7.The values in parentheses represent the uncertainty values where available.
Virial isotherm model

Figure S1 :
Figure S1: Bulk phase density measured in situ by the magnetic suspension balance compared to the values calculated using appropriate equations of state 1 for equilibrium measurements of CO 2 and N 2 on Zeolites (a-b) H-Y, (c-d) Na-Y, (e-f) and NaTMA-Y.

Figure S2 :
Figure S2: Excess adsorbed amounts of (a) CO 2 on ZSM-5 at 293 K 2 and (b) CH 4 on Zeolite Y at 298 K 3 .The solid lines represent the reference isotherms obtained from an interlaboratory study with the uncertainty bounds represented by the shaded regions.

Figure S3 :
Figure S3: Normalized weight (MP 1 -MP 1,0 ) plotted against helium bulk density measured at 393 K for (a) Zeolite H-Y, (b) Zeolite Na-Y, and (c) Zeolite NaTMA-Y.The slope of the linear regression line is equivalent to the negative value of V 0 = V met + V s

Figure S5 :Figure S6 :Figure S7 :Figure S8 :
Figure S5: Excess adsorption isotherms of (a) CO 2 , (b) N 2 , and (c) H 2 on Zeolite Na-Y at various temperatures computed using two different values for ρ s .The filled symbols correspond to n ex computed using the NIST reference value, ρ s = 2523 kg m −3 .The empty symbols correspond to n ex computed using the measured value in this study, ρ s = 2410 kg m −3 .Panels d-f show the percentage relative deviation between the excess isotherms computed using the measured experimental value for ρ s in this study relative to those calculated using the NIST reference value for ρ s .
S1) where n s,b and n s,d [mol kg −1 ] are the saturation capacities for the two sites (fixed for all sorbates for a given material and obtained by fitting the CO 2 isotherms first), b and d [bar −1 ] are the temperature dependent adsorption coefficients, described by an Arrhenius expression with two constants, b 0 and d 0 [bar −1 ] and −∆U b and −∆U d [kJ mol −1 ] for the two sites respectively.The six fitted parameters for CO 2 are n s,b , n s,d , b 0 , d 0 , −∆U b and −∆U d .For N 2 b 0 , d 0 , −∆U b and −∆U d were fitted, and for H 2 b and d were assumed to be equal as the isotherms are linear and b 0 and −∆U b were fitted.

Table S1 :
Dual-Site Langmuir (DSL) isotherm model parameters derived from fitting the CO 2 , N 2 and H 2 isotherms.The values in parentheses represent the uncertainty values.

Table S3 :
Excess, net, and absolute adsorbed amounts of CO 2 , N 2 , and H 2 on Zeolite H-Y, Na-Y, and NaTMA-Y at different temperatures and the uncertainty values associated with them denoted by δ.